The present invention generally relates to systems for transporting vehicle tires and, more particularly, to a system and method for automatically loading and unloading vehicle tires and compressing vehicle tires for storage and/or transportation within a tire transport frame.
The tire distribution process currently requires transporting large quantities of tires from the plants where they are manufactured to the various facilities where tires are delivered to consumers and/or mounted on vehicles. Typically, the processes for transporting tires from these plants to wholesalers, retailers, and service centers involve the use of large vessels. For example, semi-trailers are used for transportation over the road, rail cars are used for transportation via rail, and shipping containers are used for transportation over water. Further, these vessels provide storage of tires prior to and after transport.
To minimize the costs associated with such storage and transportation, it is desirable to pack the tires into each storage and/or transportation vessel in such a manner as to maximize the density of tires within the vessel while providing satisfactory stability of the loaded tires and avoiding permanent deformation of the loaded tires. Maintenance of the tires under a compressive load has been found to improve the stability of the loaded tires. Unfortunately, though, compression can lead to permanent deformation of the tires in some stacking configurations. Thus, a variety of stacking arrangements have been tested, each with its inherent difficulties.
One stacking arrangement that has been used extensively is called the stovepipe. This stacking arrangement is characterized by several tires stacked directly atop one another, aligned along a single axis, the axis of rotation, which is oriented vertically. In this type of stacking arrangement, the outer diameter or treaded portion of the tires on the bottom of the stovepipe stack must absorb the load caused by the weight of the tires above. In general, stacking tires in the stovepipe configuration tend to cause the treads of the tires to bow outward such that the tires, once installed on a vehicle, track along their centerlines. If there is sufficient heat and/or time during transport and storage, the deformation can be permanent. This inherent tendency toward deformation of the stovepipe-stacked tires precludes the use of excessive compression to enhance the stability of a stovepipe stack of tires. Moreover, the volume of empty space along the central axis of each stack is not utilized.
A more desirable stacking configuration is the herringbone pattern. This configuration is characterized by the tilting of all of the tires in a row such that their axis of rotation are parallel to one another and lie substantially in the same plane, but are offset. Rows of tires are stacked atop one another with the directions of the axis of rotation of successive rows being alternated, in a single plane, approximately equally about the vertical direction. Depending on the geometry of the tires being stacked, the angle between the rotational axis of tires in successive rows varies from approximately 10 degrees to approximately 60 degrees.
Packing tires in this herringbone pattern simultaneously provides stability and efficient use of the storage and/or transportation space while preventing permanent deformation of the tires in the stack so long as the period of storage is not excessive. Typical storage periods range from a week to approximately a month. In a herringbone pattern of stacking, the outer diameter tread portion of one tire is nestled against the sidewall near the hub or bead region of another tire. Compression of the sidewall at the hub region of a tire along the axis of rotation includes less risk of creating permanent deformation of the tire than compression of the tread portion in the same axial direction. Thus, the herringbone pattern of stacking is preferred to the stovepipe stacking arrangement.
Unfortunately, however, no fully automated process or apparatus exists to stack tires in a herringbone pattern. Thus, tires are typically packed into the storage and/or transportation vessels by hand. Using conventional hand-packing techniques, however, is labor intensive, relatively slow, and inherently unreliable. It can become quite cumbersome to pack tires uniformly from the floor of the vessel to the ceiling when doing so by hand. Large tires can be difficult to manipulate manually, especially when loading tires near the top of the vessel. Hand stacking can be inconsistent and unreliable and can yield non-uniform, unstable loads. Further, there exists no reliable system or method for compressing the hand-stacked tires to improve the stability of the load.
To partially remedy these problems, devices have been developed to help in the compression of the tire stacks. These systems, however, continue to rely heavily upon manual labor to accomplish the stacking of the tires. For example, U.S. Pat. No. 5,697,294, which is hereby incorporated by reference, discloses an exemplary tire compression device. U.S. Pat. No. 5,816,142, which is also hereby incorporated by reference, discloses another tire compression device, this one being intended for use with a forklift. This device allows a preset load to compress a stack of tires as the stack is loaded into a truck trailer. Initially, the forklift elevates and supports the preset load. Then, once the tires are stacked beneath the elevated load, the forklift allows the load to be lowered against a stack of tires. As a result, the load exerts a downward pressure on the stack of tires, thereby compressing the tires. Once the initial stack is compressed, additional uncompressed tires are loaded on top of the stack until the stack reaches the ceiling of the truck trailer. Then, the forks of the forklift are raised, partially releasing the pressure applied against the compressed portion of the stack and allowing it to expand while compressing the previously uncompressed portion until the entire stack is equally compressed. This process is repeated, stack by stack, until the entire trailer is full of stacked, compressed tires. Other devices exist that load tires into a truck trailer and similarly compresses the tires within the trailer. In each of these cases, the tires are maintained in compression by the storage and/or transportation vessel itself. There is no assurance, however, that the vessel was designed or is suitable to maintain such loads. In fact, vessels are frequently damaged as a result of such use.
When the storage and/or transportation within the vessel is complete, the tires are typically manually unloaded from the vessel onto a conveyor or pallet. A variety of implements exist for such handling of tires. For example, U.S. Pat. No. 3,822,526, which is hereby incorporated by reference, discloses a device for manipulating tires. No device, however, is known in the art that sufficiently eliminates the difficulties of manually stacking tires in a storage and/or transportation vessel and unloading the compressed tires from the same vessel. Moreover, no sufficient device currently exists to eliminate the reliance on the vessel to maintain a compressive load on the tires. Further, although there are loaders for tires, for example, a machine loader and a loader to create a straight stack of tires, none of the loaders currently in the art are designed to stack tires in a herringbone pattern.
The lack of a fully automated system and method for loading and compressing tires in a storage and/or transportation vessel adds unnecessary cost to the shipment of tires. Current systems such as those described above are capable of loading tires into a vessel at the rate of approximately two tires per minute per person. Furthermore, the maximum number of workers who can efficiently cooperate to load tires into a single vessel is three. Therefore, the maximum rate at which a single vessel can be loaded is approximately six tires per minute. At this rate, a single vessel with a capacity of twelve hundred tires takes approximately three hours to fill, and a tire manufacturing plant that produces thirty thousand tires per day must have facilities for simultaneously loading approximately four vessels. If, however, the rate at which the tires are loaded could be increased, fewer vessels would need to be loaded simultaneously, and less space would be required for the loading facility. For example, if the rate at which the tires could be loaded were increased to twenty tires per minute, a vessel could be loaded every hour, and the same facility producing thirty thousand tires per day could require only one vessel to be loaded at a time. As a result, less space would be required for the loading of the tires, and more efficient product flow arrangements might be possible.
A variety of additional difficulties exist as a result of reliance on the hand loading and unloading of tires. For example, loaded tires sometimes inadvertently, and unexpectedly, release their stored energy, often causing personal injury and/or other collateral damage. Initial attempts to design a device to automatically compress a stack of tires have revealed a variety of problems. For example, where the stack of tires is compressed a first direction, such as vertical, causing it to expand in a second direction, horizontal.
It would therefore be advantageous to have a system and method for increasing the rate at which tires can be loaded into a vessel for transportation and/or storage while simultaneously increasing the density of the tires packed into each vessel. It would also be advantageous to have a system and method for loading tires into a vessel for transportation and/or storage with improved safety, reliability, and stability. It would further be advantageous to have a system and method for loading tires into a vessel for storage and/or transportation whereby the permanent deformation of the tires would be prevented. It would also be advantageous to have a system and method for automatically packing tires into a vessel in a herringbone pattern for storage and/or transportation of the tires. It would also be advantageous to have a system and method for loading tires into a vessel whereby compressive loads applied to the tires were not applied or maintained by the vessel itself and where the danger of inadvertent release of the energy stored in the compressed tires could be minimized.
In addition, it would be advantageous to have a system and method for loading tires into a vessel for storage and/or transportation whereby tires could be automatically loaded into a tire transport frame such that the tire transport frame could be moved into the vessel by forklift. It would also be advantageous to have a system and method for loading tires into a tire transport frame outside of the vessel for storage and/or transportation whereby the tire transport frame would hold the stacked tires in a compressed state and keep the stacked tires in proper alignment during shipment and storage. Finally, it would be advantageous to have a system and method for loading tires into a vessel for storage and/or transportation whereby the loading could be automatic, thereby reducing the labor, time, space, risk of injury, and cost required for loading and unloading of the tires, while enhancing the safety of the process.
The present system and method accomplishes these objectives while overcoming the above described deficiencies in the art. The system of the present invention provides an apparatus that automatically and reliably stacks a plurality of tires in a herringbone pattern within a tire transport frame. The tire transport frame provides a structure that retains the stacked tires in a stable, compressed state. Further, the tire transport frame may be adapted to withstand external loads so that multiple tire transport frames may be stacked atop one another for storage of tires without compressing the tires excessively. Further, the loaded tire transport frames may be easily loaded by forklift into a vessel for storage and/or transportation without requiring significant expenditures of manual labor, time, space, or cost. As a result, the instant invention enables significant improvements in reliability, cost, safety, and capacity in the storage and/or transportation of tires.
The present invention comprises a conveyor to maintain a flow of tires; a tire transport frame for receiving and retaining a plurality of tires stacked in a herringbone pattern; and a plurality of pick-and-place loader for seizing a plurality of tires from the conveyor, rotating the plurality of tires into alignment with one another as well as in complementary herringbone pattern alignment with the tires in the tire transport frame, placing the plurality of tires together, and placing the plurality of tires into the tire transport frame to propagate the herringbone pattern of the stack of tires. In addition, the system includes a control system that is able to determine the most efficient stacking configuration based on the geometries of the tires such as inner and outer diameter and tread width, or any other set of parameters indicative of same.
The method comprises providing a flow of tires on a conveyor, seizing a plurality of tires from the conveyor, rotating the plurality of tires into alignment with one another as well as in complementary herringbone pattern alignment with the tires in the tire transport frame, placing the plurality of tires together, placing the plurality of tires into the tire transport frame to propagate the herringbone pattern of the stack of tires, compressing the herringbone pattern stack of tires within the tire transport frame, and fixing the retaining member to complete the tire transport frame.